4.1.6 Motor load jam protection 51LR
4.1.6.1 Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Motor load jam protection JAMPTOC Ist> 51LR
4.1.6.2 Function block
GUID-E6B45EAE-D0FA-4310-AA47-6F03A7B5EBBE V2 EN
Figure 135: Function block
4.1.6.3 Functionality
The motor load jam protection function 51LR is used for protecting the motor in stall or
mechanical jam situations during the running state.
When the motor is started, a separate function is used for the startup protection, and 51LR
is normally blocked during the startup period. When the motor has passed the starting
phase, 51LR monitors the magnitude of phase currents. The function picks up when the
measured current exceeds the breakdown torque level, that is, above the set limit. The
operation characteristic is definite time.
The function contains a blocking functionality. It is possible to block the function outputs.
4.1.6.4 Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are “Enable” and “Disable”.
The operation of 51LR can be described with a module diagram. All the modules in the
diagram are explained in the next sections.
1MAC059074-MB A Section 4
Protection functions
615 series ANSI 285
Technical Manual
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